cpu throttling--what is it? - Debian

This is a discussion on cpu throttling--what is it? - Debian ; Could someone explain to me (or point me to where I can find an answer) what CPU throttling is? My sony vaio has 8 CPU throttling levels: $ cat /proc/acpi/processor/CPU0/throttling state count: 8 active state: T0 states: *T0: 00% T1: ...

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Thread: cpu throttling--what is it?

  1. cpu throttling--what is it?

    Could someone explain to me (or point me to where I can find an answer) what
    CPU throttling is? My sony vaio has 8 CPU throttling levels:

    $ cat /proc/acpi/processor/CPU0/throttling
    state count: 8
    active state: T0
    states:
    *T0: 00%
    T1: 12%
    T2: 25%
    T3: 37%
    T4: 50%
    T5: 62%
    T6: 75%
    T7: 87%

    I see that varying the setting has a big effect on performance (and presumably
    battery life). However, the throttling setting doesn't seem to affect my CPU
    clock. So how does it work?

    Thanks

    Luca


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  2. Re: cpu throttling--what is it?

    Luca Pireddu:
    > Could someone explain to me (or point me to where I can find an answer) what
    > CPU throttling is? My sony vaio has 8 CPU throttling levels:


    It is a cheap replacement for real performance states (and probably
    doesn't give you much additional battery lifetime, if at all). If you
    throttle your CPU down by 50%, you can think of it as if your CPU does a
    NOOP at every second cycle. So you just lose speed, but your CPU's
    temperature may drop a bit. It won't save much power because you still
    have the same CPU voltage and you still have the same instructions to
    compute. It just takes longer and you need less power to cool your
    system.

    J.
    --
    I am on the payroll of a company to whom I owe my undying gratitude.
    [Agree] [Disagree]


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  3. Re: cpu throttling--what is it?

    On Mon, 29 Aug 2005 09:27:18 -0600
    Luca Pireddu wrote:

    > Could someone explain to me (or point me to where I can find an
    > answer) what CPU throttling is? My sony vaio has 8 CPU throttling
    > levels:


    It's described in ACPI documentation, here:
    http://acpi.sourceforge.net/document...processor.html

    --
    Marcin Bis
    http://akademia.linuksa.pl/
    #!/ Akademia Linuksa


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